In A Streetcar Named Desire by Tennessee Williams, why does Blanche say that she has left her teaching job to visit Stella?

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focuses on an aging Southern belles attempt to find a place for herself in
her sisters life.  Her encounters with her aggressive brother-in-law force her to retreat into a
place in her mind that can handle the horrors she faces. All of the characters are flawed and
psychologically fragile.  But it is Blanche DuBois who loses her last hope for
survival.

At one time, Blanche was the belle of her plantation and town. When
her husband killed himself, Blanche never recuperated from his loss.  Stella, her sister, left
Belle Reve and moved to New Orleans where she married a brutish man, Stanley. 

Now, Blanche comes to New Orleans in hopes that she can find a life with her sister.
Stella is all that Blanche has left.  As an English teacher, there has been some
scandal.

Blanche: €¦You havent asked me how I happened to
get away from the school before the spring term ended. 

Stella: Well, I
thought you would volunteer that informationif you wanted to tell me.

Blanche: You thought Id been fired?

Stella: No, I thought you might
have---resigned

Blanche: I was so exhausted by all Id been through
my---nerves broke.  I was on the verge oflunacy, almost! So Mr. Graves suggested that I take a
leave of absence€¦

Blanche tends to stretch the
truth. Although she does not tell her sister, Blanche has lost her job. Blanche has always been
delicate; she has suffered a bit of a breakdown.  This is the excuse that Blanche uses to
explain why she leaves her job. Her nerves are broken. She also tells Stella that the plantation
has been lost to bankruptcy.

Actually, Blanche resents that she had to stay
at home and take care of the family.  Stella has made a new life for herself and is now
expecting a baby.  Blanche is also horrified that her sister is living in a dump like this one
when they both come from such a wealthy, elite background.

Blanche is her own
worst enemy.  She does not mince words about her displeasure in Stella or herself having to stay
in such crummy accommodations. Stanley does not like Blanche intruding on his life; he is
infuriated when he hears that Stellas part of the plantation has been lost.

It is obvious that Blanche has a drinking problem. This fact and her attempt to create
a fa§ade of southern comfort annoy Stanley.  He determines to find out the truth about what
happened to their plantation.

Stanley does ask around and discovers that
Blanche has been lying about what happen in her hometown. Apparently, she was fired from her job
as a schoolteacher after she was discovered having an affair with one of her high school
students. She then sank further into scandal, entertaining gentlemen callers at a place called
the Hotel Flamingo until she was asked to leave town.